5 The word “earth” was used for the oxides of group 2A by the ancient scientists.Alkaline earth metals, after the alkali metals, are secondary metals with strong metallic properties.The group 2A elements are less active than those of 1A, but more active than those of group 3A.Except Be, all form ionic compounds.Be forms mostly covalent compounds.

6 The atomic radius increases from top to bottom.The melting point, boiling point and the hardness of the elements decrease from top to bottom.Beryllium is the hardest alkaline earth metalBarium is the softest alkaline earth metal.Malleable and ductile.Excess Mg+2 and Ca+2 in water means that it is hard.

8 All isotopes are radioactiveMinerals of Some Alkaline Earth MetalsBerylliumCalciumBariumBeryl,Be3Al2(SiO3)6Limestone (marble),CaCO3Barytes,BaSO4MagnesiumGypsum,CaSO4.2H2OWitherite,BaCO3Dolomite,CaCO3. MgCO3Fluorite,CaF2RadiumCarnallite,KCI.MgCI2.6H2OStrontiumAll isotopes are radioactiveEpsom salt,MgSO4.7H2OCelestite,SrSO4Strontianite,SrCO3

9 Chemical PropertiesThey are Covered by their oxides when they are exposed to air.Burn in air with bright flame.Activity of the metals increases from Be to Ba.Reactions of Ca, Sr and Ba are easy with water.Reactions of Be and Mg with water are difficult.

17 MagnesiumTo increase the hardness, durability and resistance to corrosion of alloys.Additive in rocket fuels and signal rockets.Mg(OH)2 is used as a stomach antacid.

18 Calcium CompoundsConstruction materials, bleaching agents.CaO in the production of some chemicals, steel, glass, paper and sugar.CaC2 is used to produce acetylene gasfor welding.In fertilizers andtoothpaste

19 Barium and Its CompoundsBa is used as a gas absorbent in vacuum tubes.The alloys of Ba with Ni donate electrons so used in vacuum tubes and in ignitors and spark plugs.Barium nitrate and barium chlorate are used to obtain green light in fireworks.

20 Barium and Its CompoundsBaSO4 is used to take the photos of stomach and intestines.Ba does not allow X-rays to pass like all elements with large atomic number.The Ba+2 ion is toxic, but since the solubility of BaSO4 in water is very low, its poisonous effect disappears.

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